Vigna silvestris (Syn: Vigna mungo (L.) Hepper var. silvestris Lukoki et al.) ;
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Vigna luteola (Jacq.) Benth.SN july 16 : 7 posts by 4 authors. Attachments (2).
Vigna luteola (Jacq.) Benth, prostrate herb run wild near Mangalore and Udupi, Karnataka, Is it introduced as a ground cover?

Is there any specific character that you assigned this taxon to Vigna luteola ?
Can’t it be Vigna radiata (or any of its varieties )?
And its can’t be either V. vexillata (as you’ve named the pics), since V. vexillata has pink petals.

A reply from an expert:
“The specimen attached herewith seems to be Vigna silvestris. Need photo of mature pod for confirmation. This form is found in the Karnataka. It is highly variable species. “


Still I believe it to be Vigna luteola (Jacq.) Benth, I will refer BSI Herbarium and confirm, it is reported in India, it is an introduced green cover/fodder


Vigna mungo and allied –

Stems and pods beset with tomentum :- pods are hairy in the attached photographs; but not sure of stem, probably not hispid.
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I think maybe possible.
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Vigna vexillata (L.) A.Rich is synonym of Vigna hirta Hook., has yellow-green flowers (see also FoP and FoC).
So, I think flower colour is not decisive factor and it can be V. vexillata (L.) A. Rich as well or likely!!!


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ID for Vigna spp ? : 3 posts by 2 authors. Attachments (5)
This is vigna spp but correct ID,
my think it may be sublobata or setulosa ? or silvestris?
Black seeds
it in wild form
found in Shivamogga, Karnataka


Pl. check with comparative images & latest publications at Vigna 


Thank you for email. The species of genus Vigna shall correctly identify on the basis of seed coat and seed hilum, and some species shows similar morphological characters.
The given photographs are good and more enough for the primary identification clue.
So, please check the species it could be Vigna sylvestris, but check the seed coat is it porous or shiny and seed hilum protruded/intruded. 

 


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References:
GRIN  Section Ceratotropis of subgenus Ceratotropis of Vigna (Leguminosae – Papilionoideae) in India with a new species from northern Western Ghats by M.M. Aitawade*, S.P. Sutar, S.R. Rao1, S.K. Malik2, S.R. Yadav and K.V. Bhat3- Rheedea Vol. 22(1) 20-27 2012- (KeysVigna hainiana, Vigna mungo, Vigna radiata, Vigna silvestris, Vigna sahyadriana, Vigna sublobata & Vigna subramaniana)